Update PR template to be more descriptive (#72)

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,6 +1,16 @@
-*Issue # (if available)*:
 
-### Description of changes
+#### Background
+* What do these changes do? 
+* Was a new example added? If so, what does it demonstrate?
 
+#### Testing
+* How did you test these changes?
+* Was an integration test added for any new examples? 
+* If a new example was added did you update the `smithy-templates.json` file?
 
+#### Links
+* Links to additional context, if necessary
+* Issue #, if applicable (see [here](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword) for a list of keywords to use for linking issues)
+
+---
 By submitting this pull request, I confirm that my contribution is made under the terms of the MIT-0 license.